Aqueous synthetic resin solutions and dispersions which are used as bonding compositions for printing inks, wood and metal paints, and coatings for paper and synthetics, are usually based on water soluble alkyl resins, polyacrylates, or polyesters. Alkyd resins are those with a carboxyl group, such as maleic acid, modified oils, oil modified alkyds, and oil free polyesters. In addition to a neutralizing agent component, usually an amine such alkyl resin compositions also usually contain a co-solvent. Paints based on polyacrylates are usually copolymers of acrylic acid derivatives, which can be combined with melamine- or urea resins, or combined with polyurethanes. Modified, unsaturated polyester compounds present in the form of an emulsion are usually used as polyester resin solutions.
Such bonding compositions develop foaming problems during manufacture and use due to the presence of emulsifiers and salt forming carboxyl groups. As a rule, such foaming problems cannot be solved by the use of known defoaming agents. Therefore, when using the prior art alkyl polysiloxanes in the form of an emulsion or solution in hydrocarbons in paint compositions, severe surface problems occur on the painted surfaces which are known to the expert as crater, fish eyes, and orange peel effects. Another disadvantage is that paint mixtures containing silicic acid or aluminum oxide will quickly settle out and lower the surface luster in glossy paints. The addition of other known foam inhibiting agents such as those based on mineral oils or ester oils with long chain, linear fatty acids, even with the addition of emulsifiers, are still not compatible with the bonding compositions, and weeping on the painted surface will occur. German Patent Nos. DE-OS 23 45 335, DE-OS 24 43 853, DE-OS 25 18 053, DE-OS 25 34 250, and DE-OS 28 29 906 disclose polysiloxanes and polysiloxane copolymers that exhibit greater polarity, and after adding silicon oxide or aluminum oxide, or after their dissolution in organic solvents, such as low-molecular glycols, ketones, or esters, a spontaneous defoaming action occurs. However, these compositions still exhibit the above cited disadvantages due to their mineral additive content.
German Patent No. DE-OS 30 11 304 discloses mixtures consisting of polysiloxane-polyether-block polymers, mineral oils or fatty acid esters, emulsifiers, and fatty acid alkaline earth metal and aluminum soaps. Such mixtures can be used for defoaming synthetic resin dispersions and clear lacquers; they are also effective in the absence of silicon dioxide.